I made a literature search for the most biomass-dense forests on Earth. The forest types whose highest values are over 1000 tons/hectare have been listed below. I have named the forest types after the tree species with most biomass, with the exception of the last type where the biomass distribution between the two dominant species has not been specified. In all other types the named species have over twice the biomass of the second most important species. Other species may be more numerous, e.g. in the Sequoiadendron stand, Abies lowiana (= A. concolor var. lowiana) is much more numerous but the former contains much more biomass. It is well known that Sequoia sempervirens forests are the most biomass-dense but it is less well known that the best Eucalyptus regnans stands are not far behind, one factor being about 25% higher wood density. Only above-ground live biomass is included.

The biomass values are not fully comparable. In some stands (especially S. sempervirens and Picea - Tsuga) the biomass of all the components, including tree leaves and herbs, has been calculated. In some stands (e.g. A. procera, Pseudotsuga and Sequoiadendron) only the stem biomass is included. In a few stands (e.g. E. regnans), it is difficult to say which components have been included, therefore I did not make any adjustments. Anyway, most of the biomass is in the tree stems (in the case of the Picea - Tsuga stand 88%), so the stem biomasses should be relatively close to the total biomasses. In Agathis australis, a much higher proportion of the biomass is in the branches; anyway, the value for the Agathis stand includes branches, too. In three cases, only stem volume was given; for them, I calculated biomasses by multiplying the volumes by the wood densities I found on the Internet, mainly from source #10. Those values are shown in italics. The reliability of the sources may also differ.

For the Picea - Tsuga type, I averaged the biomasses of the two most massive 0.4 ha plots in the same location, because I wanted the stands to have, if possible, at least ~1 ha sample area to be comparable. If only the most massive plot is used, the value is 1078 t/ha.

My list may well be affected by accessibility of information. A further candidate for the list could be, for example, the Taiwania - Chamaecyparis forests of Taiwan. Other Eucalyptus species, like E. delegatensis, could also make the list.

It is well known that although tropical rainforests have much higher productivity they are not as biomass-dense as the western coniferous forests. However, the best stands are not far from making the list: the most massive value I have found is 873 t/ha for lowland evergreen dipterocarp rainforest in Sebulu, East Kalimantan. The value has been achieved by a very exact destructive sampling, though the sample area is only 0.125 ha (11).

For comparison, values for the eastern US and Europe would be useful. The highest value I have found for Europe is 788 t/ha. The site is Cozzo Ferriero Reserve, an almost pure Fagus sylvatica forest at 1700-1750 m a.s.l. in southern Italy. The site has been undisturbed since about 1930. Wood volume of 1383 m3/ha has been reported, though the plot size is only 0.16 ha (14). I used wood density 0.57 g/cm3 (15).

A note about the significance of high biomass values: It is too easy to draw the conclusion that an extremely biomass-dense forest is a place "full of life". However, most of this biomass is dead wood inside the tree boles where its significance to other organisms (apart from loggers and big tree enthusiasts) is limited.

This is very interesting Kouta. I'd be curious to see how forest of the southern Appalachians stack up- such as those old groves in the Smokies. Do any NTSers have any data on forest biomass for the eastern US?

Anyway, most of the biomass is in the tree stems (in the case of the Picea - Tsuga stand 88%), so the stem biomasses should be relatively close to the total biomasses.

In terms of the NZ kauri (Agathis australis), this assumption may not hold true. The only full measurement of wood volume of a large kauri (that I know of) was done by Bob van Pelt on Tane Mahuta in 2002 (and reported here). The stem was 255 m3, total wood volume 516 m3. Almost all other data for kauri volumes is stem or merchantable volume (generally based on cbh, height of bole and a factor for taper - generally between 5% and 10%). This method dates back to the 19th century, and somewhere there is a paper from the 50's or 60's that shows that this tends to underestimate the volume by 5 to 10% when checked by tape-wraps.

Anyway BvP measured ~ 49% of the wood volume in the stem, 38% of the wood volume in the branches, and the remainder (presumably) in the top logs above the first fork. The 255 m3 stem measurement was a little bigger than the official 244 m3 "merchantable" volume that kauri are ranked on. A little over half of the mass of the tree was not in the primary stem.

The Trounson Kauri park is exceptional, in that it is the best remaining stand of kauri dominated forest. The other large forests containing old growth kauri tend to be mixed kauri/podocarp/broadleaf forests. I've only been there once, in a much younger form, but it always struck me for the density of the kauri crowns emerging from the undergrowth. I cannot find a photo looking over the park, but google street view does convey some of the majesty here: http://goo.gl/maps/tWF8O. There is a old photo of similar grove, which is a favourite of mine, as it shows a kauri stand, just before it was felled for timber (see attached). Finally, there was a particular tree called the Trounson big tree, but it was not at the park, but named after the person who preserved the park. The Trounson big tree would be one of the largest, if not the largest, if it were still standing, but it burnt down in the first decade of the 20th century. Wikimedia has an image of it, and I have attached it below.

I would guess a lot of it is just where the calculations have been done. The two RNAs in Oregon and Washington don't strike me as places that are exceptionally unique being mid-elevation forest in the Cascade Mounbtains. Any number of forests in the Coastal Ranges of Oregon, British Columbia, or the Olympics of Washington would be higher, I'd think, because of wetter conditions, less sever winters, and deeper soils.

The architecture of kauri is very different from the northern conifers, indeed. Anyway, branches and leaves are included in the biomass estimate for the kauri stand. For the methods, see source #4. I added a sentence about this to my text above.

Although Trounson Kauri Park is the most massive kauri stand, the very biggest individuals (Tane Mahuta etc.) are not there? Right?

The Goat Marsh stand is stated by many authors as the most massive stand outside the redwoods. E.g. Forest Giants of the Pacific Coast by Van Pelt, p. 94: "Southwest of the mountain [Mt. St. Helens]... is another beautiful grove, which not only contains the tallest known living Abies, but also has the Pacific Northwest biomass record... excluding coast redwood stands."

Why are the coastal forests not as biomass-dense as some forests in the Cascades? There are better members in this forum to answer. I think one reason is that stand-replacing fires are very rare near coast due to the humid conditions. Consequently, dense Douglas-fir stands are much more rare and the main shade-tolerant species, western hemlock (Tsuga heterophylla) that is much smaller tree, occupies high proportions of the forests. Shrub cover is much denser, too, and may prevent dense stands of large species from being established. Note that Douglas-fir and noble fir (Abies procera) are long-lived pioneers; dense stands of these species are often even-aged and regenerated after stand-replacing disturbances. The dominant noble firs and Douglas-firs in the Goat Marsh stand have regenerated in approx. 1630-1655.

Another reason could be the commonness of tree falling winds along the coast.

Van Pelt tells about a dense 350-year-old Douglas-fir grove in the Olympics, called "Miracle Acre". It may be more massive than the Middle Santiam RNA stand but I haven't found any numbers.

eliahd24 wrote:This is very interesting Kouta. I'd be curious to see how forest of the southern Appalachians stack up- such as those old groves in the Smokies. Do any NTSers have any data on forest biomass for the eastern US?

I found two studies on this topic. The first one is Whittaker, R. H. (1966): Forest dimensions and production in the Great Smoky Mountains. Ecology, Vol. 47, No. 1, pp. 103-121. The second one is Busing, R. T., Clebsch, E. E. C. & White, P. S. (1993): Biomass and production of southern Appalachian cove forests reexamined. Can. J. For. Res.23: 760-765. The latter appears to be more reliable: newer methods, larger sample plots; in addition, the plots and the data are partly the same; Busing, Clebsch and White have analysed Whittaker's data with better methods.

The highest estimate is 621 t/ha at Surrey Fork at 870 meters in Tsuga-Acer-Fagus-Aesculus forest. However, the plot size is only 0.1 ha. The highest value for a plot about 1 ha is 471 t/ha at Roaring Fork at 1140 meters in Tsuga-Halesia-Aesculus forest. The plot size is 1.0 ha.

Leaves and branches have been included in the estimates. According to the authors, the most massive plots are located in particularly densely wooded areas in old-growth forests.

I must decrease my estimate for an exceptional European old-growth forest. My estimate was based on Leibundgut's data from Perucica Nature Reserve. He only gives estimates for stem volumes. I calculated biomasses from the wood densities and estimated the understory and leaf biomasses from the values and the percentages of the Picea-Tsuga stand in Oregon. The latter was a mistake because the forests with an important Fagus-component has much sparser understories and also less leaf biomass. My new best guess is 700 t/ha. Fagus has much denser wood than conifers, and Abies alba reaches large dimensions and may grow in dense stands. I changed the value in my text above.

Still one note: A reason that the cove forests of the Smokies don't have more biomass is that they are so diverse: many of the tree species have smaller stature. I have read that more pure Tsuga canadensis forests may have over 600 t/ha.

Stimulated by your interest in the highest bio-mass values for forests, I've started reviewing data that I've collected over the years in MTSF, Cook Forest, Bryant and other outstanding white pine forests in the Northeast. I'm assuming that your using metric tons in the tons/hectare statistic.

Preliminary calculations point to some of the Mohawk areas as supporting upwards of 500 tons/Ha. However, I doubt that the mass ever makes it to 600, certainly no entire hectare holds that much. However, areas of the Pocumtuck Grove, Trees of Peace, and Algonquin Groves do exceed 500. As they get older, the stands thin, and even though individual tree size increases, the overall stand volume/mass does not increase. My current belief is that maximums for the white pines are reached for stand ages between 100 and 150 years. Beyond that age range, I believe that standing mass is lost through self-thinning faster than gains from increased tree size can make up the difference. I expect that there is ample forestry data that sheds light on the accumulation of mass as a function of stand age. But the data almost certainly have been developed from highly managed stands and with stand age cutoffs that don't apply to unmanaged forests.

Early on, I set out to develop a variety of statistics for Mohawk's white pine stands for the DCR. Nobody was doing it and it seemed to me that the data could be useful as a baseline for natural stand development. However, it soon became apparent that the Bureau of Forestry was not interested in the data so I began concentrating on collecting data along lines of my particular interests. Given the current day interest in biomass accumulation for carbon sequestration, I think I will double down and see if I can get a better handle on woody biomass in the Mohawk and probably Bryant white pine stands. But for the present, we might consider 500 tons/Ha as representing the best of the white pine forests in the Northeast.

One of my lists on white pines for Massachusetts covers the pines that I've modeled that have trunk volumes of 500 ft^3 or more. I've resisted going to meters^3 because when converted, the volumes are such small numbers that it doesn't seem sensible to be fretting over them. However, I'll likely express my lists in both English and metric units in the future.

Bob

Robert T. LeverettCo-founder and Executive DirectorNative Native Tree SocietyCo-founder and PresidentFriends of Mohawk Trail State Forest